Wire Rope

Failure to read, understand, and follow manufactures instructions may cause death or serious injury.



7 X 19
Aircraft Cable
6 X 19
Aircraft Cable
Size W.L.L
Max load
Weight per
100 Ft
Size W.L.L
Max load
3/16 840 lb 4200 lb 6.5 lb 3/16    
1/4" 1400 lbs 7000 lbs 11 lbs 1/4" 1060 lbs 5300 lbs
5/16" 1960 lbs 9800 lbs 17.30 lbs 5/16" 1640 lbs 8200 lbs
3/8" 2880 lbs 14400 lbs 24.30 lbs 3/8" 2360 lbs 11800 lbs
1/2" 4560 lbs 22800 lbs 45.80 lbs 1/2" 4120 lbs 20600 lbs
5/8" 7000 lbs 35000 lbs 71.50 lbs 5/8" 6440 lbs 32200 lbs


 6 x 19 IWRC Wire rope sling capacities - Flemish Eye - Ansi B30.9 - 5/1 Safety factor

Wire Rope
Q & T Carbon
Minimum shackle
size for D/d > 1
At Load Connection

  Shackle Size Vertical Choker Two Leg 60 Degree
Sling Angle
45 Degree
Sling Angle
1/4" 5/16" 1120 lbs 820 lbs 2200 lbs 1940 lbs 1500 lbs
5/16" 3/8" 1740 lbs 1280 lbs 3400 lbs 3000 lbs 2400 lbs
3/8" 7/16" 2400 lbs 1840 lbs 4800 lbs 4200 lbs 3400 lbs
1/2" 5/8" 4400 lbs 3200 lbs 8800 lbs 7600 lbs 6200 lbs
5/8" 3/4" 6800 lbs 5000 lbs 13600 lbs 11800 lbs 9600 lbs

Measuring rope diameter

diameter.gif (16723 bytes)
There is only one right way to measure rope diameter.
Use machinist's calipers and be sure to measure the widest diameter. The drawing on the top compare the
correct way with the incorrect way.

This method is not only useful for measuring the diameter of the rope, but also for determining the amount of wear and compression that has occurred while the rope has been in use.
Accurate recording of this information is essential in helping to decide when to replace the wire rope.

Wire rope is normally made slightly larger than its catalog (or nominal) size. The following chart lists the size tolerances of wire rope.

Nominal Rope Diameter Tolerance
Under          Over
0 - 1/8"  -0             +8%
Over 1/8" - 3/16"  -0             +7%
Over 3/16" - 5/16"  -0             +6%
Over 5/16"

 -0             +5%

Wear and Abuse

All wire ropes should be thoroughly inspected at regular intervals. The longer it has been in service or the more severe the service, the more thoroughly and frequently it should be inspected. Be sure to maintain records of each inspection.

Inspections should be carried out by a person who has learned through special training or practical experience what to look for and who knows how to judge the importance of any abnormal conditions they may discover. It is the inspector's responsibility to obtain and follow the proper inspection criteria for each application inspected.

Here's what happens when a wire breaks under tensile load exceeding its strength. It's typically recognized by the "cup and cone" appearance at the point of failure. The necking down of the wire at the point of failure to form the cup and cone indicates failure has occurred while the wire retained its ductility.

This is a wire with a distinct fatigue break. It's recognized by the square end perpendicular to the wire. This break was produced by a torsion machine that's used to measure the ductility. This break is similar to wire failures in the field caused by fatigue.

A wire rope that has been subjected to repeated bending over sheaves under normal loads. This results in fatigue breaks in individual wires -- these breaks are square and usually in the crown of the strands.

An example of fatigue failure of a wire rope subjected to heavy loads over small sheaves. The breaks in the valleys of the strands are caused by "strand nicking." There may be crown breaks, too.

Here you see a single strand removed from a wire rope subjected to "strand nicking." This condition is a result of adjacent strands rubbing against one another. While this is normal in a rope's operation, the nicking can be accentuated by high loads, small sheaves or loss of core support. The ultimate result will be individual wire breaks in the valleys of the strands.


Typical Evidence of Wear and Abuse

A "birdcage" is caused by sudden release of tension and the resulting rebound of rope. These strands and wires will not be returned to their original positions. The rope should be replaced immediately.

A typical failure of a rotary drill line with a poor cutoff practice. These wires have been subjected to continued peening, causing fatigue type failures. A predetermined, regularly scheduled cutoff practice can help eliminate this type of problem.

This is localized wear over an equalized sheave. The danger here is that it's invisible during the rope's operation, and that's why you need to inspect this portion of an operating rope regularly. The rope should be pulled off the sheave during inspection and bent to check for broken wires.

This is a wire rope with a high strand -- a condition in which one or strands are worn before adjoining strands. This is caused by improper socketing or seizing, kinks or dog-legs.  At top, you see a close-up of the concentration of wear. It recurs every sixth strand in a 6 strand rope.

A kinked wire rope is shown here. It's caused by pulling down a loop in a slack line during handling, installation or operation. Note the distortion of the strands and individual wires. This rope must be replaced.

Here's a wire rope that has jumped a sheave. The rope "curled"as it went over the edge of the sheave. When you study the wires, you'll see two types of breaks here: tensile "cup and cone" breaks and sheat breaks that appear to have been cut on an angle.

tecrir13.jpg (2918 bytes)
Drum crushing is caused by small drums, high loads and multiple winding conditions.


In accordance with good rigging and maintenance practices
All rigging equipment and hardware should be inspected periodically
for wear, abuse and general adequacy.


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Page maintained by peter@rigging.net . Created: 7/24/96 Updated: 9/20/01